Zn doped δ-MnO2 nano flakes: An efficient electrode material for aqueous and solid state asymmetric supercapacitors

Publication date: 30 August 2018
Source:Applied Surface Science, Volume 450
Author(s): A.V. Radhamani, M. Krishna Surendra, M.S. Ramachandra Rao
Asymmetric supercapacitors based on aqueous and solid-state electrolytes are useful for a variety of applications. The birnessite δ-MnO2 is one of the efficient materials from the MnOx family characterized by large interlayer distance (∼7.3 Å) and high theoretical specific capacitance (∼1370 F g⁻¹). However the main concern which hinders its usage for practical applications is its low electronic conductivity (∼10⁻⁶ S cm⁻¹). There are different means to enhance the conductivity and in the present studies, two simultaneous methods viz; a method of synthesis of nano-flakes along with Zn-doping in δ-MnO2 is implemented. A specific capacitance of ∼466 F g⁻¹ at a current density of 0.5 A g⁻¹ is obtained for an optimum Zn doping concentration of 1 mol% which is almost two times more than the corresponding pristine one. Both aqueous and solid-state asymmetric supercapacitor devices are fabricated using Zn doped δ-MnO2 as electrode material which can be easily scalable to industrial level. A lab-scale demonstration prototype is constructed which essentially validated the charging of solid-state supercapacitor using battery and allowing the supercapacitor to discharge through a red-LED by means of a two-way switch.

Graphical abstract

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